The microwave power satellite: What will happen if Pandora opens the Joule box?

Abstract

In the wake of dwindling supplies of fossil fuels and of mounting opposition to nuclear energy, the Solar Power Satellite (SPS) is emerging as a seriously considered source of energy. Launched by rockets of terrestrial or of lunar origin, the satellite would be inserted into geosynchronous orbit, would extend giant vanes to capture sunlight that would be converted to microwaves, and would beam the microwaves to the earth's surface where they would be trapped and transformed to direct current by a massive rectifying antenna. The potential costs of the SPS system, which may result in 100 to 200 orbiting satellites early in the 21st Century, are being reticulously weighed by officials and scientists of the Department of Energy and of the National Aeronautics and Space Administration. The benefits of a virtually continuous supply of "clean" energy must be assayed against the costs of raw materials and acquisition of land, the effects of rocket-fuel effluvium on the atmosphere, the influence of the microwave beam on the ionosphere, and the potential perturbation of ecological systems by microwave fields above and at the periphery of rectifying antennae. The scope of the risk-benefit analyses transcends national boundaries; indeed, agreements on an international scale would be necessary--and could be expanded to make the SPS system a multinational venture. However, long before the launching of the first satellite, a concensus would have to be reached as to the safety and practicability of the system. Of primary concern in this, the first phase of assessing impact, re biological and ecological effects of continuouswave microwave energy at power densities that would approximate 25 mW/cm2 near the center of the rectifying antenna and would fall to microwatt levels at the perimeter of the so-called ar a of exclusion. Currently unknown, but under investigation, are the effects of continuous, long-term microwave irradiation on airborne species that may traffic across the rectifying antenna and on other species that may inhabit the environs of the exclusion area. The extant data on biological effects of microwaves are too limited to provide "hard" predictions on the effects of continuous radiation over decades of time, but do indicate several areas in need of clarification. Of especial concern is whether airborne birds, bats, and beneficial insects such as the bees will be able to sustain flight through microwave fields of relatively high density--or whether they will learn to avoid these fields. The allusion to Pandora in the title serves as symbolic recognition of the banes and blessings that were carried in and released from the legendary Box. One notes, too, that it was Prometheus who filled the Box, the same Prometheus who stole fire from the Gods and gave it to mankind. The solar power satellite is Pandora's Joule Box. Any attempt to steal the sun's fire would move her hand to the catch. Only by diligent exercize of caution and wisdom can we hope to secure the blessings and to contain the potential perils of this marvelous device.